[SOLVED] application segfaults when assigning pixmap for Label

[dqqw]

i am writing a qt4 gui application which has the following:
-a main window with a widget which will hold:
-an ogre instance (that is not important now, it is left empty)
-a dockwidget with 2 buttons: one will cause the rendering of an image and show a dialog window, the other button just shows/hides the dialog window
-a dialog window to show the image (i have read somewhere that i should just put a label and use setpixmap to assign a pixmat to it)

here are my sources: http://pastebin.com/HXkT3Jut
here are the ui files: http://pastebin.com/0TKKDziv

the segfault happens at this line:
raytracerRenderDialog->renderedImageContainer->setPixmap(QPixmap::fromImage(renderedImage));

a few notes:
-i know that the way i implemented on_actionShow_render_triggered and on_actionRender_triggered is not the correct way, it is just temporary to see how it works
-the application flow is like this: press render button -> generate raw image pixels -> show generated image in dialog

[SGaist]

Hi and welcome to devnet,

Can you check that the QImage is valid ? e.g. do you have Tux.png in the same folder as your application executable ?

[dqqw]

i'm pretty sure that it loads the image, because when i run it in debug mode, in the locals it displays the resolution of the image

[SGaist]

You should confirm it with a test like

@
if (!renderedImage.isNull())
qDebug() << "invalid image";
@

On a related note, you can create a QPixmap from a file, that would save you the conversion there

[dqqw]

modified the code as follows:
@void RaytracerMainWindow::on_actionRender_triggered()
{
QImage renderedImage;
renderedImage.load("Tux.png");
if(!renderedImage.isNull()){
qDebug() << "invalid image";
}else{
qDebug() << "image loaded";
}

raytracerRenderDialog->renderedImageContainer->show();

//raytracerRenderDialog->renderedImageContainer->setPixmap(QPixmap::fromImage(renderedImage));

ui->actionShow_render->setChecked(true);

}@

it outputs "image loaded "

and on a sidenote raytracerRenderDialog->renderedImageContainer->show(); crashes the application

could you please take a look at the RaytracerRenderDialog class?
i think the problem comes from there.

see i created a mainwindow (RaytracerMainWindow) and a dialog (RenderDialog), the creator generated the correct headers and classes for them.
but when i tried to instanciate a RaytracerRenderDialog inside RaytracerMainWindow, the compiler threw all kinds of redefinition error and such.
so i read somewhere i must derive a class to be able to instantiate it.
i think something is messed up in the constructor of RaytracerRenderDialog.

in the past few yeard i coded mostly strictly in C, so it is hard for me to get back to the C++ mentality, let aloge getting used to QT's own mechanisms.

thanks

[SGaist]

You are doing the test wrong, if isNull() is true you have an invalid image

Are you sure renderedImageContainer is initialized correctly ?

[dqqw]

yeah, that was a copy-paste problem, and it did not have the tux.png next to it because i moved the project folder and the build folder changed too...
yeah and i copy pasted your code without actually checking... :D

i THINK i initialize it correctly:
@RaytracerMainWindow::RaytracerMainWindow(QWidget *parent):
QMainWindow(parent),
ui(new Ui::RaytracerMainWindow)
{
ui->setupUi(this);
raytracerRenderDialog= new RaytracerRenderDialog(parent);
}@

which calls this:
@RaytracerRenderDialog::RaytracerRenderDialog(QWidget *parent):
QDialog(parent),
renderDialog(new Ui::RenderDialog)
{
renderDialog->setupUi(this);
}@

somewhere in the middle i realized that qt widget classes keep a reference to themselves as a pointer of ther class, but some things are not very clean to me

if it would help i could upload an archive of the project itself

[SGaist]

Where is renderedImageContainer declared ?

[dqqw]

since it was added with the desginer:

<widget class="QLabel" name="renderedImageContainer">
<property name="styleSheet">
<string notr="true">background-color: rgb(128, 128, 128);</string>
</property>
<property name="text">
<string/>
</property>
</widget>

so it is declared in the intermediary ui_renderdialog.h, which is generated.

i assumed it should be initialized since i call the setuUi method for RenderDialog from RaytracerRenderDialog

[SGaist]

Did you run your application through the debugger ?

[dqqw]

solved it.

added
@void RenderDialog::setRenderedImage(QPixmap pixmap)
{
ui->renderedImageContainer->setPixmap(pixmap);
}@

to RenderDialog

and called it like this from raytreacermainwindow:
@void RaytracerMainWindow::on_actionRender_triggered()
{
QImage renderedImage;
renderedImage.load("Tux.png");
if(renderedImage.isNull()){
qDebug() << "invalid image";
}else{
qDebug() << "image loaded";
}

RenderDialog *renderDialog= new RenderDialog();

renderDialog->setRenderedImage(QPixmap::fromImage(renderedImage));

renderDialog->show();

}@